Heterostructure Cu3P−Ni2P/CP catalyst assembled membrane electrode for high-efficiency electrocatalytic nitrate to ammonia

Electrochemical nitrate reduction reaction (NO 3 RR) is a promising means for generating the energy carrier ammonia. Herein, we report the synthesis of heterostructure copper-nickel phosphide electrocatalysts via a simple vapor-phase hydrothermal method. The resultant catalysts were evaluated for electrocatalytic nitrate reduction to ammonia (NH 3 ) in three-type electrochemical reactors. In detail, the regulation mechanism of the heterogeneous Cu 3 P−Ni 2 P/CP− x for NO 3 RR performance was systematically studied through the H-type cell, rotating disk electrode setup, and membrane-electrode-assemblies (MEA) electrolyzer. As a result, the Cu 3 P−Ni 2 P/CP−0.5 displays the practicability in an MEA system with an anion exchange membrane, affording the largest ammonia yield rate ( R NH3 ) of 1.9 mmol·h −1 ·cm −2 , exceeding most of the electrocatalytic nitrate reduction electrocatalysts reported to date. The theoretical calculations and in-situ spectroscopy characterizations uncover that the formed heterointerface in Cu 3 P−Ni 2 P/CP is beneficial for promoting nitrate adsorption, activation, and conversion to ammonia through the successive hydrodeoxygenation pathway.